1. Field of the Invention
The goniometer of this invention relates to the measurement of the angular displacement of a device or thing, relative to the gravitational vertical.
2. Description of the Prior Art
This disclosure teaches an encoding optical goniometer for measuring angular displacements of a device or thing with respect to the gravitational vertical. Related devices are shaft encoders for measuring the rotation of a stepping motor, roll indicators such as used in aircraft or a leveling device as used in topographic surveying. Such devices are usually equipped to provide an electrical or optical readout signal. The output signal may be analogue such as might be obtained from a rotary resolver, or digital such as might be produced by a binary shaft encoder. Digital output signals may be encoded in binary, octal or hexadecimal format. If necessary, ambiguities of .pi. radians are resolved by suitable means.
Many previous devices are designed to measure angular displacement with respect to an arbitrary reference. In the invention to be disclosed, I measure the absolute angular displacement referenced to the gravitational vertical.